Neil Armstrong and Buzz Aldrin became the first humans to walk on the moon on July 20, 1969 as part of the Apollo 11 mission. After landing the lunar module Eagle on the moon's Sea of Tranquility, Armstrong radioed back to mission control "Houston, Tranquility Base here. The Eagle has landed." Armstrong was the first to step onto the lunar surface, saying his famous words "That's one small step for man, one giant leap for mankind." The astronauts conducted experiments, collected moon rocks, and planted an American flag before returning to the Eagle for their trip back to Earth.